privatedata – Arbitrary, private information set by the vendor of the font. Font vendors could use this to include any data that they deem necessary. Optional.

The fontdata file would contain the actual font file. The name does not have an extension so that it can be format agnostic. The format of the font file is specified by the element in the info.xml file. Initially the only supported format would be “opentype”. (This covers both OTF-CFF and OTF-TTF.)

As stated above, these files would be compressed into a single file. We propose .zip as the compression format. If there is another compression format that would be easier for the browsers to implement, we are open to suggestions. An informal test showed an average 40% file size savings over the raw OpenType fonts.